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Miller" , Networking , "Alexei Starovoitov" , Daniel Borkmann , Martin Lau , Yonghong Song , Andrii Nakryiko , =?iso-8859-1?Q?Toke_H=F8iland-J=F8rgensen?= Subject: Re: [PATCH bpf-next] libbpf: Add support for dynamic program attach target Thread-Topic: [PATCH bpf-next] libbpf: Add support for dynamic program attach target Thread-Index: AQHV4aBmkuDy8vU+NUWdt8DKhmBCX6gX0g0AgAAGM4A= Date: Wed, 12 Feb 2020 17:56:29 +0000 Message-ID: <628E972C-1156-46F8-AC61-DB0D38C34C81@fb.com> References: <158151067149.71757.2222114135650741733.stgit@xdp-tutorial> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3608.60.0.2.5) x-originating-ip: [2620:10d:c090:400::5:f48e] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 6c219fb5-16fd-4e8d-ba87-08d7afe4e374 x-ms-traffictypediagnostic: MW2PR1501MB2107: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-fb-source: Internal x-ms-oob-tlc-oobclassifiers: OLM:126; x-forefront-prvs: 0311124FA9 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(366004)(199004)(189003)(2906002)(76116006)(4326008)(66556008)(8676002)(81166006)(64756008)(66446008)(66946007)(66476007)(6486002)(6916009)(498600001)(81156014)(54906003)(8936002)(2616005)(71200400001)(6512007)(33656002)(5660300002)(36756003)(6506007)(53546011)(86362001)(186003);DIR:OUT;SFP:1102;SCL:1;SRVR:MW2PR1501MB2107;H:MW2PR1501MB2171.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:3; received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: OPxDwwuSjVy/8FKkbh+A3LqbkQobhN2IEpCDxT/G4YV+fXlcuCRWhC1ijz1V0D+T7/Ys8/UkgO5tZPiPdTPqfP+BiOCHKIOFNVw28AaiYd+cRUZhEbbjzXJUCRQE4rm91fdc+xdbCyhJd617oFNdbuZphRDgC3CFl6V4LdwQbykdoz1FVYx5ha2P38b0uK0qoYE7MmBspXOdlukXLwC9S0BnUgvjvsjKeVP4Dg4obkbCck1Mv5bl5nSsh+uWGk0j8VYZaDCKdSp34xkQHP7cCLeG6EHED87Et6iRKKlQSDnCJzra4GJO7x235OCswWBMgGTPe1T4y+545bUmbUeilHmjn7YPdqTu21nueZV7O4OlvgLKDY2paP5MI5uvwYx0SfbYfiE5lnGZfkU3hFOO8CFF/aGz7Q6qtn1I8i+HuB4AOQKzrl7sVrugZz2Vq8ul x-ms-exchange-antispam-messagedata: xg0169nJQMjFiS7+9eHbMjvc0h6k1lJ3bQlbPTROLdInCS/+LpI3MT2dmXcKm457dXTEDm2eIa6PJGLPJN8slX2AJ5TAYeMzrFoY+I/VBd/juZ3IAOZPP/QSP+pPj6z7FzyqdrB1YeaDZkHQqIRaayniFZ8KDvqK+o3eArU1L49DW+YIYU+W8BVPGO+EDlue Content-Type: text/plain; charset="iso-8859-1" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 6c219fb5-16fd-4e8d-ba87-08d7afe4e374 X-MS-Exchange-CrossTenant-originalarrivaltime: 12 Feb 2020 17:56:29.8047 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: TshWmRQHFugPmasMBvfm4MbRKHqrNgeF5mhnn/fnEzkvtUzWWPB5kfFYQB4TSFuzSTXoa7aKfoNELo13iCCT9w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW2PR1501MB2107 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-12_08:2020-02-12,2020-02-12 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 mlxscore=0 clxscore=1011 malwarescore=0 adultscore=0 suspectscore=0 bulkscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002120132 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > On Feb 12, 2020, at 9:34 AM, Andrii Nakryiko = wrote: >=20 > On Wed, Feb 12, 2020 at 4:32 AM Eelco Chaudron wrot= e: >>=20 >> Currently when you want to attach a trace program to a bpf program >> the section name needs to match the tracepoint/function semantics. >>=20 >> However the addition of the bpf_program__set_attach_target() API >> allows you to specify the tracepoint/function dynamically. >>=20 >> The call flow would look something like this: >>=20 >> xdp_fd =3D bpf_prog_get_fd_by_id(id); >> trace_obj =3D bpf_object__open_file("func.o", NULL); >> prog =3D bpf_object__find_program_by_title(trace_obj, >> "fentry/myfunc"); >> bpf_program__set_attach_target(prog, xdp_fd, >> "fentry/xdpfilt_blk_all"); >> bpf_object__load(trace_obj) >>=20 >> Signed-off-by: Eelco Chaudron I am trying to solve the same problem with slightly different approach.=20 It works as the following (with skeleton): obj =3D myobject_bpf__open_opts(&opts); bpf_object__for_each_program(prog, obj->obj) bpf_program__overwrite_section_name(prog, new_names[id++]); err =3D myobject_bpf__load(obj); I don't have very strong preference. But I think my approach is simpler?=20 Thanks, Song diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 514b1a524abb..4c29a7181d57 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -238,6 +238,8 @@ struct bpf_program { __u32 line_info_rec_size; __u32 line_info_cnt; __u32 prog_flags; + + char *overwritten_section_name; }; struct bpf_struct_ops { @@ -442,6 +444,7 @@ static void bpf_program__exit(struct bpf_program *prog) zfree(&prog->pin_name); zfree(&prog->insns); zfree(&prog->reloc_desc); + zfree(&prog->overwritten_section_name); prog->nr_reloc =3D 0; prog->insns_cnt =3D 0; @@ -6637,7 +6640,7 @@ static int libbpf_find_attach_btf_id(struct bpf_progr= am *prog) { enum bpf_attach_type attach_type =3D prog->expected_attach_type; __u32 attach_prog_fd =3D prog->attach_prog_fd; - const char *name =3D prog->section_name; + const char *name =3D prog->overwritten_section_name ? : prog->secti= on_name; int i, err; if (!name) @@ -8396,3 +8399,11 @@ void bpf_object__destroy_skeleton(struct bpf_object_= skeleton *s) free(s->progs); free(s); } + +char *bpf_program__overwrite_section_name(struct bpf_program *prog, + const char *sec_name) +{ + prog->overwritten_section_name =3D strdup(sec_name); + + return prog->overwritten_section_name; +} diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 3fe12c9d1f92..02f0d8b57cc4 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -595,6 +595,10 @@ bpf_program__bpil_addr_to_offs(struct bpf_prog_info_li= near *info_linear); LIBBPF_API void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear); +LIBBPF_API char * +bpf_program__overwrite_section_name(struct bpf_program *prog, + const char *sec_name); + /* * A helper function to get the number of possible CPUs before looking up * per-CPU maps. Negative errno is returned on failure. diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index b035122142bb..ed26c20729db 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -235,3 +235,8 @@ LIBBPF_0.0.7 { btf__align_of; libbpf_find_kernel_btf; } LIBBPF_0.0.6; + +LIBBPF_0.0.8 { + global: + bpf_program__overwrite_section_name; +} LIBBPF_0.0.7;=